Reciprocal dental grinder



1 Oct. 7, 1941. SCOTT, 2,258,473

RECIPROCAL DENTAL GRINbER Filed Sept. 7, 1940 2 Sheets-Sheet 1 INVENTOR.

;r0 & Earl Scott ATTORNEY.

Oct. 7, 1941. I J. E. SCOTT 2,258,473

REGIPROCAL DENTAL GRINDER Filed Sept. 7, 1 940. 2 Sheets-Sheet 2 INVENT OR.

10,9670} Earl Scozt- ATTORNEY.

Patented Oct. 7, 1941 UNITED STATES PATENT OFFICE RECIPROCAL DENTAL GRINDER Joseph Earl Scott, Pratt, Kans.

Application September 7, 1940, Serial No. 355,831

4 Claims.

My invention relates to an improvement in reciprocal dental grinding machines. The object of my invention is to provide a machine in which measurements taken from the maxilla and the mandible (jaws), may be reproduced in the machine for the purpose of reproducing the movements of the particular mandible for the purpose of grinding false teeth to fit the particular movements of the mandible in relation to the maxilla and inclined planes, and the path of condyle.

A further object is to provide a machine of the kind mentioned in which the false teeth are so ground as to eliminate buccal pressure on the teeth, when they are in use, so as to avoid tipping of the lower plate when the teeth therein are pressed against the teeth on the maxilla and enabling one to obtain a three point contact in the biting motion of the mandible, in completion of grinding thereby establishing a compensating curve. Ihe three point contact here referred to covers the protruding and lateral contacts, and specifically the working and balance bites.

Another object is to provide a machine of the kind mentioned that is light in weight, portable, simple, sturdy and long lived, highly efficient in its work and inexpensive to manufacture and sell. These and other objects will be more fully described as this description progresses.

Now referring to the accompanying drawings:

Fig. l is a plan view of the machine in which a set of false teeth are positioned for grinding purposes.

Fig. 2 is a side view of the machine shown in Fig. 1.

Fig. 3 is a sectional view through the machine, the view being taken along the line III-III in Fig. 2, and looking in the direction of the arrows. Fig. 4 is a front view of the machine as shown in Fig. 2. Fig. 5 is an enlarged detail sectional View through the driving mechanism, the view being taken along the line V--V in Fig. 3 and looking in the direction of the arrows.

Fig. 6 is an inside face view of the permanent cam. the view being taken along the line VI-VI in Fig. 5 and looking in the direction of the arrows. v

Fig. 7 is an inside face view of the adjustable cam, the view being taken along the line VII--VII inFig. 5 and looking in the direction of the arrows.

Fig. 8 is a detail sectional view through the central portion of the machine, the view being taken along the line VIII-VIII in Fig. 1 and looking in the direction of the arrows.

Fig. 9 is an enlarged detail sectional view through the supporting posts, the View being taken along the line IXIX in Fig. 8 and looking in the direction of the arrows.

Fig. 10 is a wiring diagram for the control of the electric motor employed in driving the machine.

Similar numerals of reference designate the same parts throughout the several figures ofthe drawings.

In the drawings is shown the above mentioned machine as having a base element l I that is supported on legs l2. At I3 is a gear case that is rigidly attached to the base element l l by means of screws it. On the gear case [3 is a disc like element it that is rigidly attached to the gear case it by means of screws it that face through holes 60. in the disc and .are threaded into the gear case 13.

At l l is shown an electric motor that abuts the disc i5 and is rigidly affixed thereto by means of screws i8 that pass through the disc l5 and are threaded into the motor I1.

The motor is provided with the usual rotary driving shaft IS on which is racheted a worm drive element that is rigidly fixed on the drive shaft H! by means of a pin 2| that tightly passes through registering holes in the worm element 2%] and the drive shaft IS.

on the worm element 20 is formed a journal portion 22 that is revolvably mounted in a bearing element 23 that is rigidly mounted in an annular recess 24 formed in the gear case l3 and is so held by means of a flange portion 25 of the disc i5 which overlaps the bearing 23 and is pulled and held tightly thereagainst by the screws it which hold the disc ii: on the gear case 13.

At 26 is shown a cavity in the gear case I3 in which is positioned the worm drive element 28 and a worm gear 21 that is rigidly mounted on the central portion" of a shaft 28 that is revolvably carried in long sleeve like bearings 29 and 3B which are rigidly attached to the gear case i3 by means of screws 3| which pass through flange portions of the bearing elements 29 and 3t and are threaded into the gear case element l3.

On the outer end of that portion of the shaft 28 that is carried in the bearing 29 is an eccentric element 32 that has a flange portion 33 thereon. The eccentric element 32 is provided with an eccentrically positioned pole 34 in which is tightly fitted the outer end of that portion of the shaft 23 that is carried in the bearing sleeve 29. The eccentric element '32 is rigidly held on the shaft 28 by means of a washer 35 and a screw 36 which passes through the washer and is threaded into the end of the shaft 28 so that the washer 35 is pressed against the eccentric element 32 by the head of the screw 36 so as to definitely retain the eccentric element on the end of the shaft 28 so that as the shaft 28 is revolved, the eccentric element 32 will also be revolved.

The outer end of the bearing element 30 is pro vided with an annular recess in which is snugly seated an auxiliary bearing element 3'! that is provided with a flange portion 38 which abuts the outer end of the bearing element 38 and on which is rigidly mounted a pair of inwardly directed pin elements 39 and 49 that are snugly seated in holes in the end of the bearing element 30 so as to prevent rotation of the auxiliary bearing 3'! in the bearing element 30.

At 4| is shown a pin passing through the shaft 28 and projecting outwardly a short distance therefrom and being positioned adjacent the auxiliary bearing element 3.1.

At 42 is shown a second eccentric element that has a flange portion 43 thereon and a hole 4 therein and a pair of indentures and 46 in the inside face of the cam and positioned diametrically across the hole 44 from each other.

The eccentric element 42 is revolvably mounted on the outer end of that portion of the shaft 28 that passes through the bearing element 36 and auxiliary bearing element 31., but it is stationed on the shaft 28 by reason of the ends of the pin 4i being seated in the indentures 45 and 46 in the face of the eccentric element 42. The eccentric element 42 is held in engagement with the ends of the pin element 4.1 by means of a helical spring 4! which is under compression between the outer face of the-eccentric element 42 and a washer 48 that bears against the head 49 of a screw that passes through the washer 48 and the spring 4'! and is threaded into the outer end of that portion of the shaft "28 that passes through the bearing elements 38 and '31. The object of this arrangement will later be made obvious.

On each of the eccentric elements 32 and 42 is eccentric collars 56 and 5l respectively. The collar 5B is provided with an L-shaped arm element 52, and the collar 5! is also provided with an L- shaped arm element 53.

At 54 is a threaded shaft, one end of which passes through the foot of the L-shaped element 52 and isadjustably and rigidly attached thereto by means of nuts 55 and 56 that are threaded on the shaft 54 and screwed thereon against opposite sides of the foot ofthe L-shaped element 52. On the other end of the shaft '54 is a coupling element 5.! that is threaded on the shaft 54 and is rigidly bound in position by means of a nut 58 that is threaded on the shaft 54 and screwed against the end of the coupling element 5'! to bind and hold the coupling element 51 in its adjusted position as shown. The coupling element 51 is provided with a projecting pin 59 which serves as a means of connecting the coupling element 5! to another part of the machine as will later be described.

At 60 is a second threaded shaft, which is a duplicate of the shaft 54, and one end of which passes through the foot of the L-shaped element 53 and is adjustably and rigidly attached thereto by means=of nuts 6| and 62 that are threaded on the shaftifiil and screwed thereon against opposite sides of the foot of the L-shaped element 53. On the other end of the shaft 60 is a coupling element '63 that is threaded on the shaft 68 and is rigidly bound in position by means of a nut 64 that is threaded on the shaft 60 and screwed against the end of the coupling element 63 to bind and hold the coupling element 63 in its adjusted position as shown. The coupling element 63 is provided with a projecting pin 64 which serves as a means of connecting the coupling element 63 to another part of the machine as will later be described.

At 65 and 65 is a pair of tubular vertically po-- sitioned post elements that are rigidly mounted on an A-shaped element 61 that is slidably fixed on the base element II and positioned between upwardly extending ear like elements 68 and 69 that are integrally formed on the upper side of the base element l l and a clip element 18 the upper end of which is turned so as to lap over and engage the outer'end of the A-shaped element 61.

The clip lfl is slidably mounted on a stud H and is rigidly held in place by means of a nut 12 that is threaded on the stud H and against the clip '58 so as to bind and hold the clip l0 between the nu and the end of the base element l l and the nd of the A-shaped element 67. At 73 and H shown adjusting and clamping screws that threaded through the ears 68 and 68 and enleg ends of the A-shapcd slide element 6'! so as to rigidly bind and hold the A-shaped element 6? between the clip '50 and the ends of the screws ?3 and 14.

On the central portion of the posts 65 and 66 is a element such as 15 on which is re- VGllQbly mounted flanged roller elements 16 and H that are positioned in curved or condyle slots '18 and 19 respectively that are in curved condyle link elements 88 and BI respectively. The term condyle as here applied refers to the path of motion normally employed by the jaw during the act of chewing. The bearing 15 and the rollers '56 and 7'! are held in place on the posts '65 and'66 by means of screws 651: or 66x.

In the rear end of each of the condyle link elements 88 and 8| is a hole in which the pin elements 59 and '64 on the coupling elements 5-! and 63 are pivotally seated so that motion from the coupling elements 51 and 63 may be imparted to the condyle links and 8|.

At 82 is a V-shaped element having a plate 83 thereon forming a composite mandible element, the ends of which are pivotally mounted at 84 and 85 on the condyle links 80 and 8 I The condyle links are provided with an arm portion 86 and Si, the outer ends of which are provided with outwardly projecting pin like elements 88and 89 that-are rockably mounted on the arm elements 86 and 87. At 90 and 9| is shown adjusting screws that are threaded through the pin elements 88 and 89, the lower ends of the adjusting screws 90 and 9| are seated in sockets formed in outwardly projecting pin like elements 92 and 83 that are rockably mounted on the leg portion of the mandible 82.

On the front of the mandible element 82 is rigidly mounted an outwardly projecting pin-94 for the support of the mandible element as will later be explained.

At 95 and 96 is shown brace elements, the bot-' tom ends of which are rigidly attached to the base element H by means of screws 91a and 98d that pass through slots in the foot of the braces 85 and 96 and are threaded into the base element 11. The upper end of the'brace elements :95 and 96 are 'bent over so that they are positioned behind and rest against the .upper-ends of 61167130563 65 and 66 and serve to steady theupper ends of theposts65and66.

At 9! is a T-shaped support element and the outer ends of the head of the T are provided with pin elements 98 and 99 that are rigidly mounted on the T-shaped element and are so spaced apart that they may be entered into the upper ends of the tubular posts 65 and 66 and after the pin elements 90 and 99 are rigidly fastened therein by means of set screws I and [UL At I02 is a maxilla plate that underlies the leg of the T-shaped support 91 and is slidably held thereagainst by means of a saddle slide I03 that isrigidly attached to the maxilla plate by means of screws I04 that pass through thesaddle slide I03 and are threaded into the maxilla plate I02.

Rigidly mounted on the saddle slide element IE3 is an upwardly projecting stud I for purposes that will later be explained. On the end of the leg of the T 9? is rigidly mounted a stud d element I03. At I0! is a screw that passes through and is revolvably mounted in the stud I08 and is threaded through the stud I05 and is provided with a head It'lc'by which the screw Illl may be turned, and the turning of which will move the saddle I03 and maxilla plate I02 carried thereby will be moved forward or backward as desired along the leg of the T shaped support element 0?. At I08 is a collar that is pinned to the screw 01 and functions to prevent longitudinal movement of the screw I01 through the stud I00 and, thereby force the longitudinal movement of the saddle I03 and maxilla plate I02 along the leg of the T 91 upon rotary movements of the screw I01.

At 39 is shown an elastic band that is looped over the shank of the screwhead 101a and under the pin 94 on the mandible element 82 so asto yieldably draw the mandible element 82 toward the maxilla plate for purposes that will later be described. m

At I I0 is shown an upper set of false teeth that are held in a plaster cast mounting III that is rigidly held on the maxilla plate I02 by means of screws IE2 that pass through the maxilla plate I02 and are threaded into the plaster cast mounting III. 4 a

At H3 is a lower set of false teeth that are mountedon a plaster cast mounting H4 and are rigidly mounted on the mandible plate 33 by means of screws H5 that pass through the mandible. plate 83 and are threaded into the plaster cast mounting II4. I I,

The rnachine is operated by an electric motor Ill that is controlled by a combination switch H6 and rheostat I i! that is carried in a housing IIB that is carried on the under side of the base element H and is operated by the swinging of the lever II-iia. At [I9 is shown a cable carrying the electric feed wires I and I2I and between the base plate I I and the motor I! is shown the wire I20 continuing to the motor I1, and the wire I22 connecting between the rheostat II! and the motor I'I.

Now having fully described the machine, its use and operation is as follows: The false teeth are prepared and placed in their respective mountings or plates as usual. This having been done, the plates are mounted on the plaster cast elements III and H4 and then rigidly attached to their respective maxilla and mandible plates I02 and 83 by means of the screws H2 and H5 as previously described. Now by adjusting the screws 90 and 9| the condyle links 80 and BI are rocked in rotation to the mandible plate element 83*82 reproduce or compensate for the particular shape and movement of the mandible on-which the false tooth plate H3 is to be used. Further adjustments to reproduce the movements of the mandible on which the false teeth are to be used may be made by loosening the nuts 55 and 56, and BI and 62 and then moving the shafts 54 and B0 forward or backward through the foot of the L-shaped arms 52 and 53 to the desired position and then tightening the nuts 55 and 50, and BI and 62 against their respective foot of the L-shaped arms 52 and 53. These adjustments are made from measurements previously taken from the mandible on which the false teeth are to be used.

These adjustments having been made, the screw I 01 may now be turned, whereupon, the upper set of false teeth are moved forward or rearward to the correct position relative to the lower set of false teeth. All of the proper adjustments now having been made, a suitable grinding compound is placed on the contacting surfaces of the upper and lower false teeth and then the elastic band I09 is positioned around the shank of the screw head IBM and the pin element 94 whereupon the lower false teeth are drawn with yieldable pressure against the upper false teeth.

Now the eccentrics 32 and 42, which are set in corresponding positions on the shaft 28, and the motor I! is started, whereupon the shaft 28 and eccentric elements 32 and 42 are revolved and produce a reciprocal motion that is imparted to the condyle links and 8| which in turn impart a reciprocal and upwardly rocking motion to the mandible plate and the false teeth carried thereby. During this movement the false teeth in both plates are ground to a perfect protruding lit. The false teeth having thus been ground, the eccentric element 42 may be pulled outwardly against the pressure of the spring 41 and thereby released from engagement with the pin 4| whereupon the shaft 28 will continue to revolve but the eccentric element 42 will stand still. Now the eccentric element 42 may be released whereupon the spring 4! will press the eccentric element 42 against the pin M and as the shaft 28 revolves the pin 4| will align itself with the indentures 46 and be seated therein whereupon the eccentric element 42 will again be driven in a rotary and reciprocal motion the same as before but the eccentric element 42 will be positioned. on the shaft 28 opposite to that of the eccentric 32 whereupon the motions imparted to the mandible plate element 82-83 by the eccentric 32 is opposite to the motion imparted to the mandible plate element 82-83 by the eccentric 42. The result of this adjustment is that a lateral swinging motion the same as that of the mandible in the motion of chewing is imparted to the mandible plate element 82-83 whereupon the false teeth are further ground to fit together under that movement. The false teeth thus ground, it is obvious that they will fit and properly engage each other under all conditions of protrusion and chewing, therefore there will be no tendency of the plate to tip or otherwise become dislocated in the process of chewing.

It should be here stated that the various movements imparted to the mandible plate simulate the natural movements of the jaws during the process of chewing. The teeth are properly ground on a threepoint contact including the protruding and lateral motions. The teeth when properly ground will interlace when in alignment as is the case when the jaw is at rest. Further, this grinding insures proper contact for both the working and balance bites, the proper balance bite being essential to insure' against separation of the teeth opposite those on the working or chewing side. Lack of this contact for balance is the direct cause of tilting of the lower denture.

While I have shown and described what is probably the preferred form of my invention, it is to be understood that such modifications of the invention as falls within the scope of the appended claims shall be considered as being included in my invention. Now having fully shown and described my invention, what I claim is:

l. A denture grinding machine for upper and lower sets of false teeth by a three point contact action comprising a maxilla and mandible plates, adjustable means both vertically and longitudinally for the maxilla plate, supporting means for the mandible plate, adjustable both longitudinally and laterally, posts carried by the supporting means, rotatable guide means carried by the posts, arcuate condyle links engaging the guide means, link means connecting the'arcuate links with the mandible, driving cams carried. b yi1 e machine, means connecting the cams with the arcuate links, power means for driving the c a r ns, one of said cams adjustable with respect to the other, said links and said cams adapted to impart a protruding and lateral motion to the mandible in a simulated condyle path.

2. A denture grinding machine for upper and lower sets of false teeth, means for grinding the teeth by a three point contact, comprising a maxilla and a mandible for the support of the upper and lower teeth respectively, means for rigidly supporting the maxilla in vertical adjustment, means for pivotally supporting the mandible comprising a slidable frame, posts carried by the frame, rollers carried by the posts, arcuate condyle links engageable with the rollers, adjustable and pivotal connecting means between said links and the mandible, resilient means for moving the mandible toward the arcuate maxilla, means for shifting the condyle links in unison, said last-named means adjustable for shifting the arcuate condyle links in opposing directions, said arcuate links servingto impart motion to the mandible in a protruding and lateral direction and in a simulated condyle path.

3. A reciprocal dental grinding machine of the character described for grinding upper and lower sets of false teeth on a three point contact action comprising a maxilla plate for the support of the upper teeth and a mandible for the support of the lower teeth, a mounting frame, supporting posts carried thereby, adjustable means for said frame, a bracket carried by the posts for rigidly supporting the maxilla, rollers carried by the posts, arcuate condyle links engageable with said rollers, means for pivotally and adjustably connecting the mandible with the condyle links, resilient means for moving the mandible toward the maxilla, a pair of driving cams, links connecting the cams to the condyle links, one of said cams rotatably adjustable with respect to the other, said cams when in one position serving to move the condyle links in the same direction and when in an adjusted position serving to move the condyle links in opposed directions, the movement of said condyle links imparting motion to the mandible in a protruding and lateral direction and in a simulated path of condyle.

4. In a reciprocal dental grinding machine, in combination, a base element, a gear case carried thereon, a shaft rotatable in the case, a gear on said shaft, power means for driving said gear and shaft, an eccentric element rigidly mounted on one end of the shaft, a second eccentric mounted on the opposite end of the shaft, said last-named eccentric being axially and rotatably adjustable upon the shaft, a support post frame, said support post frame being detachably connected to the base element and provided with a pair of spaced supporting posts rigidly mounted thereon, each of said supporting posts provided with a roller revolvable thereon at their central portions, a pair of condyle links provided with arcuate slots, said links engaging the said rollers with the rollers extending into the slots, a mandible element, the rear and side portions of said mandible being pivotally connected to one end of the said condyle links, means carried by the said condyle links for adjusting the angular position of the condyle links with respect to the mandible, adjustable means connecting the other ends of the condyle links and their respective eccentric elements, said adjustable eccentric when in a position opposite the other of said eccentrics imparting an opposed movement to the mandible through the condyle links, said mandible moving in the normal path of condyle, a support for the upper set of teeth, means for adjustably connecting the last named support to the said posts, resilient means for moving the free end of the mandible toward the upper support, and means for adjusting the upper set of teeth longitudinally with respect to the lower set carried on the mandible, said eccentrics and condyle links imparting a protruding and lateral motion to the lower teeth on a reciprocal plane and in a true condyle path.

JOSEPH EARL SCOTT. 

